This invention generally relates to tie-back or anchored walls, and is specifically concerned with a system and method for adjustably interconnecting the wall facing panels of a tie-back wall to the soldier beams of such a wall despite variations in the distances between the panels and the beams caused by normal misalignments or tolerances of the beams.
Tie-back walls are commonly used as both temporary and permanent earth retaining structures. Typically, such walls are built by first installing a row of uniformly-spaced soldier beams in the earth to be retained. The soldier beams may either take the form of concrete caissons, H-piles, I-beams, channels or the like. When the soldier beams are formed from concrete caissons, a hole is first augured in the earth, a reinforcing structure of steel is then laid in the hole, and the caisson is then cast from concrete. When H-piles or I-beams are used as the soldier beams, they are typically driven into the ground with suitable heavy equipment. For reasons which will become evident shortly, it is important that in either case, the soldier beams be both uniformly spaced from one another, and further be oriented plumb with respect to the earth. After the soldier beams have been installed, the earth is excavated along one side of the beams to expose a cut face of earth, and to partially expose the front faces of the beams. The soldier beams are then securely anchored to the mass of earth behind them by means of a plurality of tie-backs which are installed in the earthen mass and connected to the soldier beams. Lagging in the form of sprayed shotcrete or lagging timber is then installed to temporarily retain the cut face of earth vertically in place. A leveling pad may next be installed in front of the front faces of the beams, and pre-cast wall facing panels may then be stacked in rows to form the finished face of the wall. To complete the wall, the back faces of the wall facing panels are structurally connected to the front faces of the soldier beams, and the gap between the soldier beams and the stack of wall facing panels may be filled either with concrete, or with a water draining, granular material such as gravel.
While such tie-back walls have proven to be an economical and effective means for retaining a bank of earth, problems are created when the row of soldier beams are either not properly aligned with respect to one another or are not plumb with respect to the ground. Such misalignments cause the distances to vary between the front faces of the soldier beams and the back faces of the wall facing panels. This problem is particularly acute when driven piles are used as the soldier beams, since large rocks or other obstructions in the ground can deflect a pile away from a plumb orientation as it is being driven into the earth. If the connecting system used to structurally connect the back of the wall facing panels with the fronts of the soldier beams does not compensate for the variations in the distances between these two components, the misalignment of the beams can become transmitted to the panels after the panels are connected to the beams, thereby seriously compromising not only the esthetics of the resulting wall, but its ability to perform its intended earth-retaining function as well.
Systems for adjustably interconnecting pre-cast wall facing panels to the soldier beams of a tie-back wall are known in the prior art. In some of these systems, adjustable coupling members in the form of brackets or elongated, threaded bolts structurally interconnect the wall facing panels to either pile type or caisson type soldier beams. The space between the wall facing panels and the beams is then backfilled with gravel or the like. Such connection systems are disclosed in U.S. Pat. Nos. 4,913,594 and 5,002,436.
Unfortunately, the applicants have observed a number of shortcomings associated with such prior art adjustable connection systems. For example, in the system disclosed in U.S. Pat. No. 4,913,594, special bracket components must be mounted onto the front faces of the flanges of the H-piles in general alignment with an opposing bracket component mounted on the back side of the wall facing panel. While some flexibility is obtained through the use of vertically and horizontally oriented slots in the connecting components, this connecting system cannot effectively couple the beams to the panels if there are any significant misalignments between the bracketing components. Because this system relies upon a plurality of hand-installed and hand-adjusted nuts and bolts for its assembly and adjustment, it requires a relatively large amount of access and space between the panels and the beams. Additionally, the machined bracket components are relatively expensive to fabricate, and time-consuming to install. While the system disclosed in U.S. Pat. No. 5,002,436 is somewhat different in structure, it suffers from the same basic shortcomings as the system disclosed in U.S. Pat. No. 4,913,594 in that it requires the fabrication of a number of relatively expensively machined threaded components which must be time-consumingly installed and adjusted in the field by hand. Finally, the coupling components used in both of these prior art systems are prone to rust or corrode since they are exposed to ambient air, soil and water, which compromises their suitability for use in a permanent structure.
Clearly, there is a need for an adjustable connecting system which does not require the use of precision-machined, threaded parts and which is quick and easy to install in the field. Ideally, such a system should be inexpensive in its use of materials, and should further be able to accommodate substantial variations in the distances between the soldier beams and the back faces of the panels caused from soldier beam misalignment. Finally, such a system should facilitate the rapid construction of the tie-back wall, and should further result in a wall which utilizes a large amount of relatively inexpensive pre-cast components and which is structurally stronger than prior art walls and which has excellent drainage characteristics and a high degree of corrosion-resistance in all of its reinforcing members.